This invention relates to detergent compositions. In particular, it is directed to the use of zeolites and silicates as phosphates replacements in detergents.
Modern household laundry detergents are formulated of a number of diverse ingredients which function together to provide efficient detersive properties under a variety of water and use conditions. In addition, it is necessary that these ingredients be processed readily to provide a uniform, easily stored product that can be utilized by the consumer without difficulty or hazard. Such laundry detergents are most often prepared by spray drying an aqueous slurry of the non-volatile ingredients to produce beads or granules. Builders are incorporated into such detergents to boost cleaning power. Phosphates, especially sodium tripolyphosphate, have proven to be desirable builders, being able to sequester hard water ions and contribute alkalinity to the system. Recently, the desirability of replacing all or part of the phosphates in certain detergent formulations has become apparent. Zeolites have been suggested and tested as ion exchange agents to replace the sequestering power of the phosphates. Numerous patents have issued disclosing detergents of this nature including U.S. Pat. Nos. 3,985,669; 4,000,094; 4,019,999; 4,066,394; and 4,072,621.
Several problems are encountered when zeolites are incorporated into detergents. Some zeolites have ion exchange rates that are too slow for proper performance. German Pat. Nos. DS 2,510,741 and DS 2,510,742 and U.S. Pat. No. 4,040,972 teach that zeolites modified with up to 30% phosphate or tartrate provide more rapid inactivation of the hard water ions. It is understandable that modification of zeolites with what are essentially sequestering agents should improve their performance in this area.
In addition, it has been found that while detergents formulated with zeolites of small particle size and a high ion exchange rate have good detersive action, the zeolites tend to agglomerate during industrial preparation of the detergents. It is probable that this agglomeration takes place in the spray dryer and results from the interaction of the zeolite with other detergent ingredients. These agglomerates lead to decreased performance and deposits on the fabric being laundered.
These and other problems prevent the use of significant amounts of alkali metal silicate in detergents formulated with zeolite builders. U.S. Pat. Nos. 3,985,669; 4,000,094; 4,019,999; and 4,066,394 teach that only a limited amount of silicate solids, 3% or less can be incorporated into zeolite built detergents. These patents indicate that larger amounts of silicate result in a decrease in the ion exchange capacity of the zeolite and also decreases the rate of hardness ion depletion. It would be advantageous to provide zeolite built detergents that contain substantially more than 3% of silicate solids since they provide important detersive and process contributions. Soluble silicates provide added alkalinity, supplemental builder properties, corrosion protection, bead formation and other functionalities which make detergent processing and use easier.
U.S. patent application Ser. No. 833,122, filed Sept. 14, 1977, now allowed, teaches the preparation of silane-hydrated zeolite composites. This application is hereby incorporated by reference.
It is an object of this invention to provide zeolite built detergents formulated with substantial amounts of soluble silicate solids. It is also an object of this invention to provide zeolite built detergents with high silicate levels that do not agglomerate in processing, storage or use.